Dry etching method and apparatus for performing dry etching

ABSTRACT

A dry etching method includes loading a wafer on a lower electrode having at least two cooling paths. Cooling fluids having different temperatures are supplied to each of the cooling paths of the lower electrode so that the multiple cooling paths are at different temperatures from one another. The wafer is etched during cooling.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a dry etching method and an apparatusfor performing dry etching, and more particularly to the dry etchingmethod and apparatus including multiple cooling paths.

(b) Discussion of the Related Art

Equipment for manufacturing semiconductor devices is generallyclassified as either equipment for preceding processes or equipment forsubsequent processes. The equipment for preceding processes is used toform a photoresist pattern on a semiconductor substrate, such as coatinga photoresist layer, exposing, and developing. In contrast, theequipment for subsequent processes is used for various processes relatedto a patterned substrate, such as an ion implantation process whereinimpurity ions are implanted into the patterned substrate, an etchingprocess wherein a target layer is selectively removed by using thephotoresist pattern, a deposit process wherein a thin film is depositedon the semiconductor substrate, and a metallization process wherein acircuit pattern is interconnected.

Etching is generally performed by either a wet etching apparatus or adry etching apparatus. The known dry etching apparatus includes a lowerelectrode disposed opposite an upper electrode in an etching chamber. Inthe known dry etching apparatus, a wafer is loaded on the lowerelectrode, and process gases are supplied and converted into plasma bythe upper electrode.

FIG. 1 shows an example of a lower electrode in the known dry etchingapparatus. As shown in the figure, the lower electrode 102 definescooling paths 104 in which cooling gas flows. A clamping part 106presses a wafer W loaded on the lower electrode 102, such that the waferW is held on the lower electrode 102, and is cooled by the cooling gasflowing in the cooing paths 104 during etching of the wafer W.

When the known dry etching apparatus is used to etch the wafer W, theuniformity in the thickness of the remaining layer after the etchingprocess depends on process conditions, such as a source power of the dryetching apparatus, chamber pressure, ratio of process gases, anduniformity of an etch target layer. The uniformity in thickness of theremaining layer is also largely dependent on a rear surface temperatureof the wafer.

FIG. 2 is a graph showing etch rate and uniformity in thickness of theremaining layer on the wafer as a function of the rear surfacetemperature of the wafer. As shown in FIG. 2, both the etch rate and theuniformity in the thickness of the remaining layer are increased as therear surface temperature of the wafer is increased.

FIG. 3 is a graph showing simulated data of the thickness of theremaining layer as a function of position after etching with the knowndry etching apparatus. As shown in FIG. 3, the remaining layer is notuniformly thick.

As described above, in the known dry etching apparatus the temperatureof the lower electrode is uniform over the entire rear surface of thewafer. However, uniformity, or lack thereof, of the deposited etchtarget layer is not accounted for during the setting of processconditions. The uniformity of the deposited etch target layer affectsthe uniformity in the thickness of the remaining layer. Therefore, it isdifficult to improve the uniformity in the thickness of the remaininglayer.

SUMMARY OF THE INVENTION

To address the above-described and other problems, it is an object ofthe present invention is to provide a dry etching method that includesloading a wafer on a lower electrode having at least two cooling paths.Cooling fluids having different temperatures are supplied to each of thecooling paths of the lower electrode so that the multiple cooling pathsare at different temperatures from one another. The wafer is etchedduring cooling.

The present invention further provides an apparatus for performing dryetching. A lower electrode defining at least two cooling paths isdisposed in an etching chamber. An upper electrode, which is configuredto convert process gases into plasma, is disposed above the lowerelectrode. A fluid supply device is configured to supply cooling fluidshaving different predetermined temperatures to the cooling paths.

The present invention further provides a method of etching asemiconductor that includes cooling a first portion of the semiconductorto a first temperature, cooling a second portion of the semiconductor toa second temperature, and etching a layer of the semiconductor duringcooling of the first and second portions.

The present invention still further provides an etching apparatusincluding an upper electrode disposed in an upper portion of an etchingchamber, and a lower electrode disposed in a lower portion of theetching chamber opposite the upper electrode. The lower electrodedefines first and second cooling path. A first fluid supply device isconfigured to supply a first coolant at a first temperature to the firstcooling path. A second fluid supply device is configured to supply asecond coolant at a second temperature to the second cooling path.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the invention,and together with the description serve to explain principles of theinvention.

FIG. 1 is a schematic diagram showing a lower electrode of a known dryetching apparatus.

FIG. 2 is a graph showing etch rate and uniformity in thickness of aremaining layer on a wafer as a function of the rear surface temperatureof the wafer.

FIG. 3 is a graph showing simulated data of the thickness of theremaining layer as a function of position on the wafer after the etchingprocess by the known dry etching apparatus.

FIG. 4 is a graph showing measured data of a thickness distribution ofan etch target layer after the layer is formed to have a predeterminedthickness.

FIG. 5 is a schematic diagram of a dry etching apparatus according tothe present invention.

FIG. 6 is a graph showing measured data of a thickness distribution ofthe etch target layer after the layer is etched by the apparatus of FIG.5.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment of the present invention is described below withreference to the accompanying drawings.

FIG. 4 is a graph showing measured data of an oxide layer thicknessdistribution in a wafer after the oxide layer is formed to have apredetermined thickness of about 8000 Å. According to the data, thethickness of the oxide layer is 8200 Å at a central portion of the waferand 8600 Å at a peripheral portion of the wafer. Thus, as indicated inFIG. 4, the oxide layer, as an etch target layer, is thicker at theperipheral portion than at the central portion. Therefore, the thicknessof the etch target layer can be non-uniform even before an etchingprocess is performed.

To prevent a deterioration of thickness uniformity of a remaining layerafter etching due to the non-uniformity in thickness of the etch targetlayer (i.e., due to a non-uniformity in the thickness of the layer to beetched before etching), the present invention uses the dry etchingapparatus as shown in FIG. 5.

As shown in FIG. 5, the dry etching apparatus includes a lower electrode12 located in an etching chamber 10. An upper electrode 14 forconverting process gases into plasma is located in an upper part of thechamber 10, opposite the lower electrode 12. One or more process gasesare supplied to the upper electrode 14 by an inflow pipe 16.

The lower electrode 12 has at least two cooling paths, and preferablythree cooling paths including a central path, an edge path, and a middlepath located between the central and edge paths. The multiple coolingpaths of the lower electrode 12 are connected to multiple inflow pipes18 a, 18 b and 18 c, respectively.

The inflow pipes 18 a, 18 b and 18 c are connected to a fluid supplydevice 18 for supplying cooling fluids having different predeterminedtemperatures to each of the inflow pipes 18 a, 18 b, and 18 c.

For example, a cooling fluid having a temperature of 10° C. can besupplied to the central portion of the lower electrode 12 by the inflowpipe 18 a, a cooling fluid having a temperature of 20° C. can besupplied to the middle portion of the lower electrode 12 by the inflowpipe 18 c, and a cooling fluid having a temperature of 30° C. can besupplied to the edge portion of the lower electrode 12 by the inflowpipe 18 b.

The dry etching apparatus according to the present invention usescooling fluids having different temperatures because the etch rateincreases as the rear surface temperature of the wafer increases, asshown in FIG. 2.

Therefore, by using the dry etching apparatus according to the presentinvention, the peripheral portion of the wafer, where the etch targetlayer is thicker, is etched to a greater degree than the central portionof the wafer. By this arrangement, uniformity in the thickness of theremaining layer is improved.

FIG. 6 is a graph showing measured data of a thickness distribution ofthe etch target layer after the layer is etched by the dry etchingapparatus of the present invention. In the etching process, a processgas of C₄F₈ is flowed at 16 sccm, Ar is flowed at 380 sccm, O₂ is flowedat 5 sccm, and CO is flowed at 300 sccm. The pressure of the processchamber is maintained at a level of 55 mTorr, and source power ismaintained at 1700 MW.

As indicated by a comparison of FIG. 3 to FIG. 6, dry etching inaccordance with the present invention provides an improvement in theuniformity in thickness of the remaining layer as compared to the knowndry etching method.

As described above, selective etching performed in consideration of thevariation in the thickness of the etch target layer can be performed bycooling different portions of the wafer to different temperatures. Bythis arrangement, the uniformity in the thickness of the remaining layerafter etching can be improved.

The above discussion is directed to a preferred embodiment of theinvention. It is to be understood, however, that the invention is notlimited to the disclosed embodiment. Rather, the invention is intendedto cover various modifications and equivalent arrangements includedwithin the spirit and scope of the appended claims.

The present application claims priority to, and incorporates byreference herein in its entirety, Korean patent application no.10-2004-0110601, filed on Dec. 22, 2004.

1-6. (canceled)
 7. An apparatus for performing dry etching, comprising:an etching chamber; a lower electrode mounting a wafer having anetch-target layer thereon, the lower electrode comprising a plurality ofcooling paths including a central cooling path and an edge cooling path;an upper electrode disposed above the lower electrode; and a fluidsupply device configured to supply cooling fluids having differenttemperatures to each of the plurality of cooling paths.
 8. The apparatusaccording to claim 7, wherein the lower electrode further comprising amiddle cooling path located between the central cooling path and theedge cooling path.
 9. The apparatus according to claim 8, wherein thefluid supply device comprises three inflow pipes configured to deliverthe cooling fluids to the central cooling path, the edge cooling path,and the middle cooling path of the lower electrode. 10-16. (canceled)17. An etching apparatus, comprising: an etching chamber; an upperelectrode disposed in an upper portion of the etching chamber; a lowerelectrode disposed in a lower portion of the etching chamber oppositethe upper electrode, the lower electrode to mount a wafer having anetch-target layer therein the lower electrode defining first, second andthird cooling paths, wherein the etch-target layer is thicker at an edgeportion thereof than at a central portion at a central portion and atemperature of the cooling fluid supplied to the central cooling path islower than that of the cooling fluid supplied to the edge cooling path;a first fluid supply device configured to supply a first coolant at afirst temperature to the first cooling path; a second fluid supplydevice configured to supply a second coolant at a second temperature tothe second cooling path; and a third fluid supply device configured tosupply a third coolant at a third temperature to the third cooling path.18. (canceled)
 19. The apparatus according to claim 9, wherein atemperature of the cooling fluid supplied to the edge cooling path ishigher than a temperature of the cooling fluid supplied to the middlecooling path, and the temperature of the cooling fluid supplied to themiddle cooling path is higher than a temperature of the cooling fluidsupplied to the central cooling path.
 20. The apparatus according toclaim 19, wherein the temperature of the cooling fluid supplied to theedge cooling path is 30° C., the temperature of the cooling fluidsupplied to the middle cooling path is 20° C., and the temperature ofthe cooling fluid supplied to the central cooling path is 10° C.
 21. Theapparatus according to claim 17, wherein the first cooling path is anedge cooling path, and the second cooling path is a central coolingpath, and the third cooling path is located between the first coolingpath and the second cooling path.
 22. The apparatus according to claim21, wherein the first temperature is greater than the secondtemperature.
 23. The apparatus according to claim 22, wherein the thirdtemperature is lower than the first temperature and greater than thesecond temperature.
 24. The apparatus according to claim 23, wherein thefirst temperature is 30° C., and the second temperature is 20° C., andthe third temperature is 10° C.